Skip to content
Kharita Challenges

Problems

Real geospatial problems, graded automatically. Choose a track, a level and what you want to hand in.

2 of 59 problems

Pick one for me
Track
Spatial Analysis1 problemPostGIS / SQL1 problemPython1 problemRemote Sensing0 problemsCartography2 problemsWeb GIS6 problemsData Management0 problemsGIS Architecture2 problems
Level
Beginner0 problemsIntermediate1 problemAdvanced1 problemExpert0 problems
Hand in
SQL0 problemsPython0 problemsGeoJSON0 problemsAnswers2 problemsSchema0 problemsDecisions0 problemsDataset file0 problems
Category
Data preparation0 problemsData quality0 problemsSpatial analysis0 problemsRaster analysis0 problemsCartography0 problemsDecision support1 problemGeospatial systems0 problemsWeb delivery2 problems
Sign in to track progress
GIS ArchitectureWeb deliveryAnswersClear all
  1. Not started, Why a cloud-optimised GeoTIFF is cheap to serveWeb deliveryAnswers

    Read a COG's internal structure — tiles, overviews, bytes — and turn it into the numbers a tile server's capacity plan rests on.

    GIS ArchitectureintermediateDifficulty: intermediate200 XP~30 min4 checks

    You hand in your answers as values.

    Datasets

    • Greater London land cover 2021 (ESA WorldCover 10 m) · Raster · EPSG:4326
    • Greater London, Sentinel-2 red and NIR, 11 July 2025 · Raster · EPSG:32630

    What you’ll do

    • Read a GeoTIFF's block size and overview structure
    • Count internal tiles from dimensions and block size
    • Relate the structure to what a tile request costs
    COGGeoTIFFtile servercapacity planningrasterAlso trains Web GIS
    Open problem
  2. Not started, Polling a live feed: what does it cost per day?Web deliveryAnswers

    Size the transfer cost of a live layer from the file as served — uncompressed, gzipped, and per day at scale — before choosing between polling and push.

    GIS ArchitectureadvancedDifficulty: advanced280 XP~35 min3 checks

    You hand in your answers as values.

    Dataset

    • Santander Cycles docking stations (live snapshot) · Point · 799 features · EPSG:4326

    What you’ll do

    • Measure a payload as served rather than as re-encoded
    • Quantify what transport compression buys
    • Extrapolate a polling design to a daily transfer figure
    capacity planningpollinggzippayloadarchitectureAlso trains Web GIS
    Open problem